Ozone water generation device and generation method

Abstract

In a state in which a solvent capable of dissolving ozone gas is circulated through a circulation line (L2a), the temperature of the solvent is appropriately controlled, and the solvent is caused to flow into a gas-liquid mixer (21) to which the ozone gas is supplied at an arbitrary supply pressure, thereby mixing and dissolving the ozone gas in the solvent. The gas-liquid mixer (21) includes a solvent flow path through which a solvent flows, and an ozone gas introduction path that is connected to the solvent flow path and introduces ozone gas supplied to the gas-liquid mixer (21) into the solvent flow path. In addition, the solvent temperature is controlled such that the solvent vapor pressure is less than the ozone gas supply pressure, and the ozone gas supplied to the gas-liquid mixer (21) has an ozone concentration of 50 vol% or more and an ozone partial pressure of 30 kPa (abs) or less.

Description

Technical Field

[0001] The present invention relates to a technology that can contribute to an ozone water generation apparatus and a generation method. Background Art

[0002] Ozone water obtained by dissolving ozone in a solvent (e.g., pure water or other raw water) has strong oxidizing ability and has been used for disinfection in, for example, water supply systems and foods. This use of ozone water is considered an environmentally friendly method because ozone easily decomposes into oxygen in the end and does not leave any residual chemicals.

[0003] In recent years, attempts have been made to use ozone water in the cleaning process for manufacturing various industrial components such as precision electronic components (e.g., semiconductor devices and display components such as FPDs), and increasing the concentration of ozone water and ensuring a stable industrial supply of ozone water have been considered.

[0004] Patent Document 1 discloses increasing the concentration of ozone water as follows: First, cooling (concentrating) ozone gas to obtain ozone water, then evaporating the ozone water again, using a cooling collector to collect the ozone gas (concentrated ozone gas) obtained by the re-evaporation, and further dissolving the collected material (liquid or solid ozone) in water to obtain ozone water.

[0005] Patent Document 2 discloses the following configuration: A cleaning liquid is obtained by simultaneously dissolving ozone gas and carbon dioxide gas in raw water (e.g., raw water at 25°C or lower (preferably, raw water at 5°C to 20°C)), and then the cleaning liquid is brought into contact with a resist film (organic film) on a substrate while heating to 45°C or higher, thereby maintaining a high concentration of ozone in the cleaning liquid and making it easier to remove the resist film.

[0006] In Patent Document 3, it is disclosed that by using a gas-liquid mixer to mix raw water with ozone gas from an ozone gas generator (in Patent Document 3, a device using oxygen as a raw material) and providing an orifice between the ozone gas generator and the gas-liquid mixer, it is possible to suppress the ozone gas generator side from becoming a negative pressure state (i.e., a state lower than atmospheric pressure (about 101.33 kPa)), thereby improving the efficiency of ozone gas dissolution.

[0007] Patent Document 4 discloses the following configuration: It includes an ozone water circulation pipeline for circulating ozone water and an ozone gas contact mechanism (a permeable membrane made of fluororesin) that causes raw water to come into contact with the discharged ozone gas discharged from the ozone water circulation pipeline, thereby increasing the concentration of ozone water by effectively using the discharged ozone gas.

[0008] In Patent Document 5, it is disclosed that raw water is mixed with ozone gas from an ozone gas generator (in Patent Document 5, a device using oxygen as a raw material) by using a gas-liquid mixer to generate ozone water, and ozone water with a concentration that is excessively reduced due to the raw water (in Patent Document 5, the ozone water in the tank represented by symbol 34) is passed through the gas-liquid mixer to increase the concentration of the ozone water.

[0009] In Patent Document 1, it is disclosed that CF4 gas is applied as an inhibitor to suppress the self-decomposition reaction in the case where a rapid self-decomposition reaction of ozone may occur due to external factors (for example, an electric spark, a triggering factor such as a pollutant that causes decomposition).

[0010] According to the configurations shown in Patent Documents 1 to 5, although it may be possible to generate ozone water having a certain ozone concentration (for example, about 100 ppm), it is considered that ozone water having a further higher concentration (for example, 200 ppm or higher in the cleaning process of semiconductor devices) is required in the cleaning process that requires a relatively high oxidation ability.

[0011] Prior art documents

[0012] Patent documents

[0013] Patent Document 1: Japanese Patent Application Laid-Open No. H11-262782

[0014] Patent Document 2: Japanese Patent No. 4296393

[0015] Patent Document 3: Japanese Patent No. 4746515

[0016] Patent Document 4: Japanese Patent No. 5213601

[0017] Patent Document 5: Japanese Patent No. 7041466

[0018] Non-patent documents

[0019] Non-patent Document 1: Taiyo Nippon Sanso Technical Report No. 28 (2009) "Measurement Equipment for Explosion Limits" Summary of the invention

[0020] For example, as shown in Patent Documents 3 and 5, in a configuration using a gas-liquid mixer, when the supply pressure of the ozone gas supplied to the gas-liquid mixer is increased (to a pressure higher than atmospheric pressure), the ozone gas may be more easily dissolved in the solvent, and high-concentration ozone water can be obtained.

[0021] However, as mentioned above, if the supply pressure of ozone gas is simply increased, as shown in Non-Patent Document 1, a rapid self-decomposition reaction of ozone easily occurs, making it difficult to maintain practical safety, and thus there is a risk that stable industrial supply cannot be achieved.

[0022] The present invention has been made in consideration of such technical problems, and an object of the present invention is to provide a technology that can contribute to the easy and stable supply of high-concentration ozone water.

[0023] The ozone water generation apparatus and method according to the present invention can contribute to solving the above problems, and in one aspect, the ozone water generation apparatus is provided with: a circulation pipeline for circulating a solvent capable of dissolving ozone gas; a control unit configured to control the temperature of the solvent; and a gas-liquid mixer, in the circulating state of the solvent circulation, the solvent flows through the gas-liquid mixer and ozone gas is supplied to the gas-liquid mixer at an arbitrary supply pressure.

[0024] In addition, the gas-liquid mixer includes a solvent flow path through which the solvent flows, and an ozone gas introduction path that is connected to the solvent flow path and introduces the ozone gas supplied to the gas-liquid mixer into the solvent flow path.

[0025] In addition, the control unit controls the temperature of the solvent so that the vapor pressure of the solvent is less than the supply pressure of the ozone gas, and the ozone gas has an ozone concentration of 50% by volume or higher and an ozone partial pressure of 30 kPa(abs) or less.

[0026] The ozone water generation method in one aspect includes: a circulation step of circulating a solvent capable of dissolving ozone gas through a circulation pipeline; a temperature control step of controlling the temperature of the solvent in the state where the solvent is circulated through the circulation step; and a gas-liquid mixing step of allowing the solvent to flow into a gas-liquid mixer to which ozone gas is supplied at an arbitrary supply pressure in the state where the solvent is circulated through the circulation step.

[0027] In addition, the gas-liquid mixer includes a solvent flow path through which the solvent flows, and an ozone gas introduction path that is connected to the solvent flow path and introduces the ozone gas supplied to the gas-liquid mixer into the solvent flow path.

[0028] In addition, the temperature control step is performed to control the temperature of the solvent so that the vapor pressure of the solvent is less than the supply pressure of the ozone gas, and the ozone gas supplied through the gas-liquid mixing step has an ozone concentration of 50% by volume or higher and an ozone partial pressure of 30 kPa(abs) or less.

[0029] As described above, according to the present invention, it is possible to contribute to the easy and stable supply of high-concentration ozone water. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1It is a schematic block diagram explaining the configuration of the ozone water generation device A according to an embodiment.

[0031] FIG. 2(a) is a graph of the saturated vapor pressure curve of water, and FIG. 2(b) is a table of vapor pressures.

[0032] Figure 3 It is a graph showing the change characteristics over time by observing the flow rate of ozone gas (O3 flow rate) supplied through the gas-liquid mixing process, the discharge amount of ozone water (O3 water extraction amount), and the ozone concentration (O3 water concentration) in the verification example. Detailed Embodiments

[0033] The ozone water generation device and generation method according to the embodiment of the present invention are completely different from the configuration that simply uses a gas-liquid mixer as shown in, for example, Patent Documents 3 and 5 (hereinafter, simply referred to as "conventional configuration").

[0034] That is, in the present embodiment, while circulating a solvent (e.g., raw water, pure water, or ultrapure water) capable of dissolving ozone gas through a circulation pipeline, the temperature of the solvent (hereinafter simply referred to as "solvent temperature") is appropriately controlled, and the solvent is caused to flow into a gas-liquid mixer supplied with ozone gas at an arbitrary supply pressure, thereby mixing and dissolving the ozone gas in the solvent.

[0035] In addition, the gas-liquid mixer is provided with a solvent flow path through which the solvent flows, and an ozone gas introduction path that is connected to the solvent flow path and introduces the ozone gas supplied to the gas-liquid mixer into the solvent flow path. Further, the solvent temperature is controlled so that the vapor pressure of the solvent is less than the supply pressure, and the ozone gas supplied to the gas-liquid mixer has an ozone concentration of 50 vol% or higher and an ozone partial pressure of 30 kPa(abs) or less.

[0036] According to the present embodiment, since a high-concentration ozone gas in which the ozone partial pressure is sufficiently reduced can be used, the occurrence of a rapid self-decomposition reaction in the ozone gas can be sufficiently suppressed, thereby maintaining practical safety. In addition, since the vapor pressure of the solvent flowing through the gas-liquid mixer is controlled to be less than the supply pressure (i.e., the total pressure) of the ozone gas supplied to the gas-liquid mixer, the ozone gas is easily dissolved in the solvent. Therefore, it can contribute to making it easier to stably supply high-concentration ozone water.

[0037] The generating apparatus and generating method according to the present embodiment are configured such that ozone gas (ozone gas having an ozone concentration of 50% by volume or more and an ozone partial pressure of 30 kPa (abs) or less) supplied to the gas-liquid mixer at an arbitrary supply pressure can be dissolved in the solvent while appropriately controlling the solvent temperature as described above. That is, technical knowledge in various fields (for example, the fields of ozone gas and ozone water generation) can be appropriately applied, and the design can be changed while appropriately referring to prior art documents as needed. As an example thereof, the following embodiments can be cited. In the following embodiments, for example, detailed explanations are appropriately omitted by using the same reference numerals for the same content.

[0038] <<Reference>>

[0039] For example, in the case of a conventional ozone gas generator (ozone generator) used in a conventional configuration, the generated ozone gas has a low concentration (for example, an ozone concentration of 20% by volume or less), and contains a large amount of gas (hereinafter referred to as "non-ozone components") due to components other than ozone (for example, oxygen). Even when such low-concentration ozone gas is used, it is difficult to generate high-concentration ozone water, and a large amount of non-ozone components are dissolved.

[0040] In addition, with respect to ozone water generated by dissolving the low-concentration ozone gas mentioned above in a solvent under high pressure to increase its concentration, in addition to ozone components, it also contains non-ozone components in a supersaturated state. When such ozone water is released into the atmosphere, bubbles are formed by the non-ozone components and these bubbles are easily dispersed in the air, and the ozone components are also more easily dispersed. As a result, the ozone water cannot be maintained in a high-concentration state.

[0041] In recent years, it has become possible to concentrate ozone gas generated by, for example, an ozone generator by using, for example, an adsorption concentration method (a method of surface adsorption using silica gel or the like) or a cooling concentration method to generate high-concentration ozone gas (for example, an ozone concentration of 50% by volume or more).

[0042] For example, a cooling concentration type ozone gas generator (product name: Pure Ozone Generator) manufactured by MEIDENSHA CORPORATION can generate an extremely high-concentration ozone gas having an ozone concentration close to 100% by volume (an ozone concentration of 90% by volume or more), and it has also passed the international safety standard (SEMI-S2) certification to ensure practical safety.

[0043] However, even for the concentrated ozone gas mentioned above, it is necessary to maintain a reduced pressure state so that a rapid self-decomposition reaction does not occur, and it is difficult to apply it to a conventional configuration (that is, a configuration that prevents the ozone gas generator side from becoming a negative pressure state).

[0044] On the other hand, in the present embodiment, since ozone gas is used in a reduced pressure state (ozone partial pressure of 30 kPa (abs) or less), it is possible to safely use the highly concentrated ozone gas that has been concentrated as described above, and thereby it is possible to generate the desired high-concentration ozone water.

[0045] In particular, when the ozone gas has an ozone concentration of 90 vol% or higher and an oxygen concentration of less than 10 vol%, by reducing the total pressure of the ozone gas to 30 kPa (abs) or less (i.e., reducing the ozone partial pressure to 30 kPa (abs) or less), it is possible to safely maintain the ozone gas.

[0046] In addition, when the ozone gas has an ozone concentration of 50 vol% or higher and an oxygen concentration of less than 50 vol%, by reducing the total pressure of the ozone gas to 60 kPa (abs) or less (i.e., reducing the ozone partial pressure to 30 kPa (abs) or less), it is possible to safely maintain the ozone gas.

[0047] <<Embodiment>>

[0048] <Example of the configuration of the ozone water generating apparatus A>

[0049] Figure 1 is a schematic block diagram for explaining the configuration of the ozone water generating apparatus A according to the embodiment. This apparatus A mainly includes: an ozone gas supply unit 1 that can supply ozone gas having an ozone concentration of 50 vol% or higher in a reduced pressure state, a circulation unit 2 that introduces a solvent capable of dissolving the ozone gas of the ozone gas supply unit 1 and circulates it (circulates it in the clockwise direction as shown in Figure 1 ), a solvent supply unit 3 that supplies the solvent and gas to the circulation unit 2, and a control unit 6 that controls the ozone gas supply unit 1, the circulation unit 2, the solvent supply unit 3, etc. by appropriately acquiring information indicating the states of the ozone gas supply unit 1, the circulation unit 2, the solvent supply unit 3, etc. (for example, the measured value of the temperature measuring resistor 24 in the circulation pipeline L2a (solvent temperature) described below; hereinafter simply referred to as "state information").

[0050] Furthermore, in the case of the apparatus A shown in Figure 1 , it is configured to have: a discharge unit 4 that discharges the solvent in the circulation unit 2 to the outer peripheral side of the circulation unit 2 (releases the solvent in which ozone gas is dissolved, i.e., ozone water), and a discharge unit 5 that discharges the gas phase gas separated from the solvent from the circulation unit 2, and each of them is controlled by the control unit 6 by appropriately acquiring state information.

[0051] <Example of the configuration of the ozone gas supply unit 1>

[0052] Figure 1The ozone gas supply unit 1 shown in the figure mainly includes an ozone gas generator 10, an ozone gas supply pipeline L1a that supplies the ozone gas generated by the ozone gas generator 10 to the circulation unit 2 (via a gas-liquid mixer 21 described below), and an ozone gas discharge pipeline L1b that is connected to the ozone gas supply pipeline L1a and is used to discharge the ozone gas in the ozone gas supply pipeline L1a (for example, to adjust the gas pressure of the ozone gas supply pipeline L1a).

[0053] In the ozone gas supply unit 1, the ozone gas generator 10 can be of any type that can generate ozone gas with an ozone concentration of 50% by volume or higher and supply it in a reduced-pressure state, and various types can be applied. As an example, a configuration that uses an adsorption concentration method or a cooling concentration method to concentrate the ozone gas generated by, for example, an ozone generator can be cited.

[0054] In addition, the adsorption concentration method is a method that uses the surface adsorption phenomenon together with silica gel to concentrate ozone gas, and if impurities such as NOx or heavy metals are mixed in the ozone gas to be concentrated, these impurities may also be concentrated during the concentration process. For this reason, if these impurities are mixed in, it is preferable to remove them in advance.

[0055] On the other hand, the cooling concentration method is a method of evaporating liquid ozone obtained by cooling the ozone gas to be concentrated. In addition, since the vapor pressure of ozone gas and impurities are different from each other (for example, at a level that differs by several orders of magnitude), the ozone gas concentrated by the cooling concentration method (the ozone gas after evaporation) contains almost no impurities in principle. Therefore, it can be said that when impurities may be mixed in the ozone gas to be concentrated, it is preferable to apply the cooling concentration method.

[0056] Next, a gas flow controller 11 is provided in the ozone gas supply pipeline L1a to control the flow rate of the ozone gas flowing through the ozone gas supply pipeline L1a. In addition, upstream of the gas flow controller 11 (on the side of the ozone gas generator 10), a pressure gauge 12 is provided, which measures the gas pressure of the ozone gas flowing on the upstream side (that is, the supply pressure of the ozone gas supplied to the gas-liquid mixer 21 described below).

[0057] Furthermore, on the downstream side of the gas flow controller 11, an on / off valve (for example, a check valve, and there are two on / off valves in Figure 1 is provided) 13 that can switch the flow of the ozone gas in the ozone gas supply pipeline L1a (to supply or reverse the ozone gas flow). Furthermore, on the downstream side of the on / off valve 13, a pressure gauge 14 that measures the gas pressure on the downstream side is provided. This pressure gauge 14 can measure the gas pressure corresponding to the suction pressure when the ozone gas is sucked through the gas-liquid mixer 21 described below, and can evaluate the suction pressure.

[0058] Next, in the ozone gas discharge pipeline L1b, a on / off valve 15 is provided which is connected in a communicating manner between a gas flow controller 11 and a on / off valve 13 in the ozone gas supply pipeline L1a and can switch the flow (discharge) of ozone gas from the ozone gas supply pipeline L1a. In addition, on the downstream side of the on / off valve 15 in the ozone gas discharge pipeline L1b, an ozone decomposer (ozone scavenger) 16 that decomposes the ozone gas flowing through the ozone gas discharge pipeline L1b into a safe state and a vacuum pump 17 that sucks and discharges the decomposed ozone gas are provided.

[0059] <Example of the configuration of the circulation section 2>

[0060] Figure 1 The circulation section 2 shown mainly includes: a circulation pipeline L2a capable of introducing and circulating the solvent of the solvent supply section 3, a circulation tank 20 connected to the circulation pipeline L2a and capable of introducing a certain amount of solvent and storing it, a return pipeline L2b that returns the solvent discharged from the circulation tank 20 to the circulation pipeline L2a, and a gas-liquid mixer 21 that mixes the solvent and ozone gas.

[0061] In the circulation pipeline L2a of the circulation section 2, the ozone gas supplied from the ozone gas supply section 1 to the gas-liquid mixer 21 is introduced into the circulation pipeline L2a via the gas-liquid mixer 21 and dissolved in the solvent. In Figure 1 In the circulation section 2 shown, the circulation pipeline L2a and the gas-liquid mixer 21 are both described as being connected and integrated together, but are not limited to this configuration, and they can be configured separately from each other.

[0062] Although an ejector, a suction pump, an ejector pump, etc. can be applied as the gas-liquid mixer 21, the gas-liquid mixer 21 is not limited to them, and various types can be applied. In other words, for the gas-liquid mixer 21, it is sufficient to have a solvent flow path (not shown in the drawings) through which the solvent flows and an ozone gas introduction path (not shown in the drawings) that is connected to the solvent flow path and introduces the ozone gas supplied to the gas-liquid mixer 21 into the solvent flow path.

[0063] According to the gas-liquid mixer 21 having a solvent flow path and an ozone gas introduction path as described above, based on Bernoulli's theorem, a suction pressure is generated in the ozone gas introduction path according to the flow rate (flow velocity) of the solvent flowing through the solvent flow path. In addition, according to the saturated vapor pressure of the solvent, vapor is generated in the ozone gas introduction path. For example, when the solvent is raw water, it has the characteristics shown in the saturated vapor pressure curve and the table of the vapor pressure of water in FIG. 2.

[0064] Based on the characteristics of the solvent shown in FIG. 2 and the supply pressure of the ozone gas to the gas-liquid mixer 21, the temperature range of the solvent (hereinafter referred to as the "suction range") can be obtained in which the vapor pressure in the ozone gas introduction path of the gas-liquid mixer 21 is lower than the supply pressure. Considering the general solubility characteristics of the gas in the solvent (the solubility tends to increase when the temperature of the solvent decreases), this suction range is preferably set to a relatively low temperature range, but at least higher than the freezing point of the solvent (the temperature at which the solvent does not freeze).

[0065] Then, by appropriately controlling the solvent temperature within the suction temperature range by the control unit 6 (as in the temperature control process described below), the vapor pressure in the ozone gas introduction path of the gas-liquid mixer 21 can be set to be lower than the supply pressure of the ozone gas supplied to the gas-liquid mixer 21. In particular, it is preferably set such that the measured value of the pressure gauge 14 is lower than the measured value of the pressure gauge 12. Thereby, it is easy to introduce the ozone gas in the ozone gas supply pipeline L1a into the ozone gas introduction path of the gas-liquid mixer 21, and the ozone gas can be dissolved by mixing it with the solvent.

[0066] On the upstream side of the gas-liquid mixer 21, a circulation flowmeter 22 for measuring the circulation flow rate of the solvent circulating in the circulation pipeline L2a is provided. On the downstream side of the gas-liquid mixer 21, a circulation pump (two circulation pumps in Figure 1 is) 23 for the circulating solvent is provided. As Figure 1 shown, by providing two circulation pumps 23a and 23b, for example, one of the circulation pumps 23a and 23b can be operated normally, and when the primary pressure of one drops too low, the other of the circulation pumps 23a and 23b can function as an auxiliary pump. However, according to the situation of the circulation section 2 (circulation conditions, etc.), the other can be appropriately omitted.

[0067] In addition, on the downstream side of the circulation pump 23, a temperature measuring resistor (two temperature measuring resistors in Figure 1 is) 24 for measuring the temperature of the solvent and a temperature controller (such as a cooler) 25 for adjusting the temperature of the solvent are provided. By appropriately controlling these temperature measuring resistors 24 and the temperature controller 25 by the control unit 6, the solvent temperature can be set to the suction range.

[0068] Next, the circulation tank 20 is provided with a cylindrical peripheral wall 20a having a bottom and can store a certain amount of solvent, and the inner wall surface of the peripheral wall 20a is formed in the following shape: having a cylindrical side wall inner peripheral surface 20b having an axis extending in the vertical direction.

[0069] Above the peripheral wall 20a, there are provided: an inlet 26 communicating with the downstream side of the temperature measuring resistor 24b in the circulation pipeline L2a (i.e., the downstream side of the gas-liquid mixer 21), an inlet 26a communicating with the pressure regulating pipeline L3c described below, and an outlet 26b communicating with the gas discharge pipeline L5 described below.

[0070] Below the peripheral wall 20a, there are provided: an outlet 27 communicating with the upstream side of the circulation flowmeter 22 in the circulation pipeline L2a (i.e., the upstream side of the gas-liquid mixer 21), and an outlet 28 communicating with the solvent discharge pipeline L4 described below.

[0071] Although the shape of the inlet 26 is not particularly limited, for example, as Figure 1 shown, the inlet 26 is provided at the position of the inner peripheral surface 20b of the side wall and is formed in a shape that opens on one side in the circumferential direction of the inner peripheral surface 20b of the side wall. According to the inlet 26 having an opening in the inner peripheral surface 20b of the side wall, the solvent introduced into the circulation tank 20 through the inlet 26 is stored in the following manner: while swirling along the inner peripheral surface 20b of the side wall, it moves downward in the vertical direction (for example, while generating a swirling flow shown by the symbol S in Japanese Patent No. 6954645).

[0072] When the solvent moves while swirling along the inner peripheral surface 20b of the side wall as described above, the liquid phase component of the solvent having a high density is more likely to move along the inner peripheral surface 20b of the side wall by centrifugal force, and the gas phase component having a low density is more likely to be condensed toward the axis of the inner peripheral wall 20b of the side wall. That is, the solvent swirling as described above makes efficient gas-liquid separation more likely to occur, and the gas phase component (gas phase gas) generated by the gas-liquid separation can be moved to the upper side of the circulation tank 20, and the liquid phase component can be stored on the lower side of the circulation tank 20.

[0073] Next, the reflux pipeline L2b is connected to communicate between the upstream side of the solvent discharge pipeline L4 described below and the upstream side of the circulation flowmeter 22 in the circulation pipeline L2a, so that the solvent on the upstream side of the solvent discharge pipeline L4 (i.e., the solvent discharged from the outlet 28) is allowed to flow back to the circulation pipeline L2a. In addition, an ozone concentration measuring instrument 29 capable of measuring the ozone concentration of the solvent flowing back through the reflux pipeline L2b is provided in the reflux pipeline L2b. By the ozone concentration measuring instrument 29 provided in the reflux pipeline L2b, instead of simply measuring the ozone concentration of the solvent in the circulation pipeline L2a, the ozone concentration of the same as the solvent actually discharged from the circulation tank 20 (i.e., the target ozone water) can be measured.

[0074] <Example of the configuration of the solvent supply unit 3>

[0075] Figure 1The solvent supply unit 3 shown in [figure] is provided with: a solvent supply pipeline L3a capable of supplying a solvent such as raw water to the circulation pipeline L2a; a concentration adjustment pipeline L3b capable of supplying a concentration adjustment gas (such as carbon dioxide gas) for stabilizing the ozone concentration of the solvent in the circulation pipeline L2a; and a pressure adjustment pipeline L3c capable of supplying a pressure adjustment gas (such as an inert gas, such as N2, Ar, and He) for adjusting the pressure in the circulation tank 20.

[0076] In the solvent supply unit 3, the solvent supply pipeline L3a is connected in a communicating manner between the circulation pumps 23a and 23b in the circulation pipeline L2a, and is provided with a solvent flow controller 31 capable of controlling the flow rate of the solvent flowing through the solvent supply pipeline L3a. Further, on the downstream side of the solvent flow controller 31, a water purification unit (such as a water purification device) 32 capable of increasing the purity of the solvent flowing through the solvent supply pipeline L3a and an on / off valve 33 capable of switching the flow of the solvent in the solvent supply pipeline L3a are provided.

[0077] Next, the concentration adjustment pipeline L3b is connected in a communicating manner between the circulation pumps 23a and 23b in the circulation pipeline L2a, and is provided with a gas flow controller 34 capable of controlling the flow rate of the concentration adjustment gas flowing through the concentration adjustment pipeline L3b. Further, on the downstream side of the gas flow controller 34, an on / off valve 35 capable of switching the flow of the concentration adjustment gas in the concentration adjustment pipeline L3b is provided.

[0078] Next, the pressure adjustment pipeline L3c is connected and communicated with the inlet 26a of the circulation tank 20, and is provided with a gas flow controller 36 capable of controlling the flow rate of the pressure adjustment gas flowing through the pressure adjustment pipeline L3c.

[0079] <Example of the configuration of the discharge unit 4>

[0080] Figure 1 The discharge unit 4 shown in [figure] is provided with a solvent discharge pipeline L4 that discharges the solvent in the circulation tank 20 to the outer peripheral side of the circulation tank 20. This solvent discharge pipeline L4 is connected and communicated with the discharge port 28 of the circulation tank 20, and is provided with a discharge flow controller 41 capable of controlling the discharge flow rate of the solvent discharged through the solvent discharge pipeline L4.

[0081] <Example of the configuration of the discharge unit 5>

[0082] Figure 1The discharge section 5 shown in the figure is provided with a gas discharge pipeline L5, which discharges the gas in the circulation tank 20 (for example, the gas-phase components generated from the solvent through gas-liquid separation) to the outer peripheral side of the circulation tank 20. Such a gas discharge pipeline L5 is connected and communicated with the discharge port 26b of the circulation tank 20, and is provided with an on / off valve (for example, a back pressure regulating valve) 51 that can switch the flow (discharge) of the gas in the circulation tank 20 while maintaining a constant pressure in the circulation tank 20. In addition, on the downstream side of the on / off valve 51, the gas discharge pipeline L5 is provided with an ozone concentration measuring instrument 52 that can measure the ozone concentration of the ozone gas flowing through the gas discharge pipeline L5, and an ozone decomposer 53 that decomposes the ozone gas flowing through the gas discharge pipeline L5 into a safe state.

[0083] <Example of the configuration of the control unit 6>

[0084] Regarding Figure 1 the control unit 6 shown in the figure, it is sufficient to be configured to appropriately acquire the state information of the ozone gas supply section 1, the circulation section 2, the solvent supply section 3, the discharge section 4, and the discharge section 5 and control them so that the target ozone water can be obtained, and various configurations can be applied.

[0085] For example, a configuration can be applied in which the control unit 6 and the devices (such as measuring instruments, regulating instruments, controllers, on / off valves, circulation pumps, temperature measuring resistors) provided in each pipeline (ozone gas supply pipeline L1a, ozone gas discharge pipeline L1b, circulation pipeline L2a, circulation pipeline L2b, solvent supply pipeline L3a, concentration regulating pipeline L3b, pressure regulating pipeline L3c, solvent discharge pipeline L4, and gas discharge pipeline L5) are appropriately connected via signal lines not shown in the figure.

[0086] According to such a configuration, the state information of the devices can be acquired by appropriately operating each pipeline, and based on the acquired state information, a control instruction can be output to the devices and they can be controlled.

[0087] <Example of the method for generating ozone water by device A>

[0088] In the device A shown above, the desired ozone water can be generated by appropriately performing the following circulation process, temperature control process, gas-liquid mixing process, discharge process, and discharge process.

[0089] First, in the circulation process, the solvent is supplied to the circulation pipeline L2a by opening the on / off valve 33 of the solvent supply pipeline L3a to fill the circulation pipeline L2a with the solvent. The amount of the solvent filled in the circulation pipeline L2a is appropriately set, for example, so that the liquid level of the solvent in the circulation tank 20 is between the inlet 26 and the outlet 27.

[0090] Then, by operating, for example, the circulation pump 23 of the circulation pipeline L2a, the circulation pipeline L2a is brought into a state in which the solvent circulates at a predetermined circulation flow rate (hereinafter simply referred to as the "circulation state"). During this circulation state, the concentration adjustment pipeline L3b and the pressure adjustment pipeline L3c are also operated as needed to stabilize the ozone concentration of the circulating solvent in the circulation pipeline L2a and adjust the pressure in the circulation tank 20.

[0091] Next, in the temperature control process, based on the supply pressure of the ozone gas in the subsequent stage in the ozone gas supply process and the characteristics shown in the saturation vapor pressure curve and the vapor pressure table in FIG. 2, the suction range is determined in advance. Then, in the circulation state, the temperature controller 25 is used to adjust the temperature of the solvent in the circulation pipeline L2a so that the solvent temperature is within the suction range, while the temperature measuring resistor 24 is used to measure the solvent temperature in the circulation pipeline L2a. For example, when the target is ozone water having an ozone concentration of 300 ppm or more, the suction range is set to be higher than the freezing point of the solvent and 15 °C or lower.

[0092] Next, in the gas-liquid mixing process, in the circulation state, ozone gas is supplied to the gas-liquid mixer 21 by, for example, opening the on / off valve 13 of the ozone gas supply pipeline L1a. Here, since the circulating solvent temperature is within the suction range through the temperature control process in the previous stage, the supply pressure of the ozone gas to the gas-liquid mixer 21 is greater than the vapor pressure of the ozone gas introduction path of the gas-liquid mixer 21.

[0093] As a result, the ozone gas supplied to the gas-liquid mixer 21 is introduced into the solvent flow path via the ozone gas introduction path in the gas-liquid mixer 21 and becomes a state in which it can be dissolved by mixing with the solvent in the solvent flow path. Therefore, by dissolving the ozone gas in the solvent, the solvent becomes a solvent having a desired ozone concentration.

[0094] In addition, when the measured value of the pressure gauge 14 becomes greater than the measured value of the pressure gauge 12 in the state where ozone gas is supplied through the gas-liquid mixing process, the on / off valve 13 is switched and controlled to the open state. Thereby, the occurrence of the reflux of the ozone gas in the ozone gas supply pipeline L1a can be suppressed.

[0095] Next, in the discharge process, in the circulation state, the solvent in the circulation tank 20 is discharged (i.e., the target ozone water is obtained) by appropriately controlling the discharge flow controller 41 of the solvent discharge pipeline L4. In addition, the discharge flow rate of the solvent is controlled by appropriately supplying the solvent from the solvent supply pipeline L3a to the circulation pipeline L2a so that it is not greater than the circulation flow rate of the solvent in the circulation pipeline L2a.

[0096] Thus, it is possible to discharge the solvent while maintaining a certain amount of the solvent stored in the circulation tank 20. That is, ozone water having a desired ozone concentration can be continuously extracted during the discharge process.

[0097] Next, in the discharging process, by opening, for example, the on / off valve 51 of the gas discharge pipeline L5, the gas present in the circulation tank 20 (for example, the gas-phase component separated from the circulating solvent) is discharged to the outer peripheral side of the circulation tank 20.

[0098] <Verification>

[0099] By using the apparatus A having the configuration shown in Figure 1 , ozone water is generated by appropriately performing the above-described circulation process, temperature control process, gas-liquid mixing process, discharging process, discharging process, etc. Then, the amount of impurities of metal and non-metal elements (Li, Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Sn, Ba, Pb, Si) contained in the ozone water is observed by inductively coupled plasma mass spectrometry (ICP-MS) at the ppb level, and the results shown in Table 1 below are obtained. In addition, when observing the change characteristics over time for the flow rate of the ozone gas supplied through the gas-liquid mixing process ( Figure 3 O3 flow rate in Figure 3 ), the discharge amount of the ozone water extracted by the discharge through the discharging process ( Figure 3 O3 water extraction amount in Figure 3 ), and the ozone concentration (

[0100] O3 water concentration in

[0101] [Table 1]

[0102] Unit: ppb

[0103] Element to be measured Na Cr Fe Cu Al Analytical value Less than 0.1 Less than 0.5 Less than 0.5 Less than 0.5 Less than 0.5

[0104] From the results in Table 1, it can be seen that the ozone water generated by the apparatus A contains almost no impurities of metal or non-metal elements, and the amounts of Na, Cr, Fe, Cu, and Al impurities are maintained below the quantification limit.

[0105] According to Figure 3As a result, it can be seen that apparatus A can continuously release ozone water with a high concentration of 300 ppm or more while maintaining a certain amount of solvent stored in circulation tank 20. It can also be seen that the ozone concentration of the ozone water remains almost unchanged. That is, it was confirmed that a stable supply of high-concentration ozone water is possible.

[0106] <Examples of applications of ozone water generated by apparatus A>

[0107] For example, in the case of a Si semiconductor, when performing a normal RCA cleaning process, Si dangling bonds may be exposed on the surface of the Si substrate. Generally, in a subsequent hydrofluoric acid treatment process or the like, the dangling bonds are hydrogen-terminated, thus suppressing the attachment of contaminants to the dangling bonds.

[0108] However, since the lifetime of hydrogen termination is short (e.g., only a few hours), if the hydrogen-terminated state is to be maintained for a long time, a thin oxide film needs to be formed on the Si substrate surface so that the dangling bonds are not exposed. That is, it can be considered that after RCA cleaning, by applying ozone water with a high concentration, an extremely thin Si oxide film is formed on the Si substrate surface. However, if the applied ozone water contains impurities of metal or non-metal elements, these impurities are incorporated into the Si oxide film, and the target Si semiconductor product cannot be obtained.

[0109] Therefore, when forming the Si oxide film as described above, by applying the ozone water generated by apparatus A, the incorporation of impurities into the Si oxide film can be suppressed, and the target Si semiconductor product can be obtained more easily.

[0110] As described above, in the present invention, although only the details of the specific examples described are explained, those skilled in the art can clearly make various changes, etc. within the scope of the technical concept of the present invention, and such changes, etc. naturally fall within the scope of the claims.

Claims

1. Ozone water generation device, comprising: A circulation pipeline for circulating a solvent capable of dissolving ozone gas; A control unit configured to control the temperature of the solvent; and A gas-liquid mixer through which the solvent flows in a circulating state of the solvent, and the ozone gas is supplied to the gas-liquid mixer at an arbitrary supply pressure, Among them, The gas-liquid mixer includes: A solvent flow path through which the solvent flows; and An ozone gas introduction path that is connected to the solvent flow path and introduces the ozone gas supplied to the gas-liquid mixer into the solvent flow path, wherein the control unit controls the temperature of the solvent such that the vapor pressure of the solvent is less than the supply pressure of the ozone gas, and wherein the ozone gas has an ozone concentration of 50% by volume or higher and an ozone partial pressure of 30 kPa(abs) or less.

2. The ozone water generation device according to claim 1, Among them, The control unit controls the temperature of the solvent to be higher than the freezing point of the solvent and 15°C or lower.

3. The ozone water generation device according to claim 1 or 2, Among them, The ozone gas has an ozone concentration of 90% by volume or higher.

4. The ozone water generation device according to claim 1, Among them, The ozone gas is supplied to the gas-liquid mixer via an on / off valve, and wherein when the vapor pressure of the solvent is greater than the supply pressure of the ozone gas, the control unit closes the on / off valve.

5. The ozone water generation device according to claim 1, Among them, The gas-liquid mixer is connected to the circulation pipeline.

6. The ozone water generation device according to claim 1, further comprising a discharge section for discharging the solvent, Among them, The control unit controls the discharge flow rate of the solvent discharged from the discharge section to be less than the circulation flow rate of the solvent in the circulating state.

7. The ozone water generation device according to claim 1, Among them, A circulation tank for introducing and storing the solvent is connected to the circulation pipeline.

8. The ozone water generation device according to claim 7, Among them, Provided on the upper side in the vertical direction of the circulation tank: a discharge section for discharging the gaseous phase gas separated from the solvent introduced into the circulation tank.

9. The ozone water generation device according to claim 7, Among them, The inner wall surface of the circulation tank has: a cylindrical side wall inner peripheral surface having an axis extending in the vertical direction, wherein the side wall inner peripheral surface is provided with: an inlet port that communicates with the downstream side of the gas-liquid mixer in the circulation pipeline and introduces the solvent from the downstream side into the circulation tank, wherein on the side lower than the inlet port in the vertical direction in the inner wall surface, provided are: an outlet port that communicates with the upstream side of the gas-liquid mixer in the circulation pipeline and guides the solvent introduced into the circulation tank to the upstream side, and a discharge port that communicates with the outer peripheral side of the circulation section and discharges the solvent introduced into the circulation tank, and wherein the inlet port is formed in a shape that opens toward one side in the circumferential direction of the side wall inner peripheral surface.

10. The ozone water generation device according to any one of claims 7 to 9, Among them, The control unit controls the pressure inside the circulation tank by supplying an inert gas to the circulation tank.

11. An ozone water generation method, comprising: a circulation step of circulating a solvent capable of dissolving ozone gas through a circulation pipeline; a temperature control step of controlling the temperature of the solvent while the solvent is circulated through the circulation step; and a gas-liquid mixing step of allowing the solvent to flow into a gas-liquid mixer in which ozone gas is supplied at an arbitrary supply pressure while the solvent is circulated through the circulation step, wherein the gas-liquid mixer includes: a solvent flow path through which the solvent flows; and an ozone gas introduction path connected to the solvent flow path and introducing ozone gas supplied to the gas-liquid mixer into the solvent flow path, wherein the temperature control step is performed to control the temperature of the solvent such that the vapor pressure of the solvent is less than the supply pressure of the ozone gas, and wherein the ozone gas supplied through the gas-liquid mixing step has an ozone concentration of 50 vol% or higher and an ozone partial pressure of 30 kPa(abs) or less.

12. The ozone water generation method according to claim 11, Among them, in the temperature control step, the temperature of the solvent is controlled to be higher than the freezing point of the solvent and 15°C or lower.

13. The ozone water generation method according to claim 11 or 12, Among them, the ozone gas has an ozone concentration of 90 vol% or higher.

14. The ozone water generation method according to claim 11, Among them, in the gas-liquid mixing step, the ozone gas is supplied to the gas-liquid mixer via an on / off valve, and when the vapor pressure of the solvent is greater than the supply pressure of the ozone gas, the on / off valve is closed.

15. The ozone water generation method according to claim 11, further comprising a discharge step of discharging the solvent, Among them, in the discharge step, the discharge flow rate of the solvent discharged through the discharge step is controlled to be less than the circulation flow rate of the solvent circulated through the circulation step.

16. The ozone water generation method according to claim 11, wherein the gas-liquid mixer is connected to the circulation pipeline.

17. The ozone water generation method according to claim 11, wherein, A circulation tank for introducing and storing the solvent is connected to the circulation pipeline.

18. The ozone water generation method according to claim 17 further includes: A discharge step of discharging a gas phase gas separated from the solvent introduced into the circulation tank from an upper side in the vertical direction of the circulation tank.

19. The ozone water generation method according to claim 17, Among them, the inner wall surface of the circulation tank has: a cylindrical side wall inner peripheral surface having an axis extending in the vertical direction, wherein the side wall inner peripheral surface is provided with: an inlet port communicating with the downstream side of the gas-liquid mixer in the circulation pipeline and introducing the solvent from the downstream side into the circulation tank, wherein, on a side lower than the inlet port in the vertical direction on the inner wall surface, there are provided: an outlet port communicating with the upstream side of the gas-liquid mixer in the circulation pipeline and guiding the solvent introduced into the circulation tank to the upstream side, and a discharge port communicating with the outer peripheral side of the circulation part and discharging the solvent introduced into the circulation tank, and Among them, the introduction port is formed in a shape that opens to one side in the circumferential direction of the inner peripheral surface of the side wall.

20. The ozone water generation method according to any one of claims 17 to 19 further includes a pressure control step of controlling the pressure in the circulation tank by supplying an inert gas into the circulation tank.

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